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Erosion and Sediment Control - Faga’alu, American Samoa

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Page 1: Erosion and Sediment Control - Faga’alu, American Samoa
Page 2: Erosion and Sediment Control - Faga’alu, American Samoa

Outline

Introduction and Objectives -

American Samoa -

Stream Sampling -

Land-Based Sources of Pollution -

Impacts -

Environmental Management Practices -

Summary -

Acknowledgements -

Page 3: Erosion and Sediment Control - Faga’alu, American Samoa

Introduction

• Steven Curtis

• The Pennsylvania State University

• Environmental Meteorology

• National Ocean Service (NOS)

– Fagatele Bay National Marine Sanctuary (FBNMS)

Page 4: Erosion and Sediment Control - Faga’alu, American Samoa

Introduction

• FBNMS a member of the Governor’s Coral Reef Advisor Group (CRAG)

• Addressed Land-Based Sources of Pollution to mitigate impacts on coral reef within Faga’alu Bay, American Samoa

• Supports NOAA’s objective

• Emily Gaskin (FBNMS) • Lauren Wetzell (AS-CMP) • Phil Wiles (AS-EPA) • Hideyo Hattori (CRAG Lead) • Rocco Tinitali (ASCC)

Page 5: Erosion and Sediment Control - Faga’alu, American Samoa

American Samoa

• Consists of Five (5) Islands

• Latitude / Longitude: 14.30S 170.70W

• Population: ~60,000

• Capital City: Pago Pago

• Faga’alu Village

http://www.nationsonline.org/map_small/samoa.jpg http://www.infoplease.com/atlas/state/americansamoa.html

Page 6: Erosion and Sediment Control - Faga’alu, American Samoa

Faga’alu

Page 7: Erosion and Sediment Control - Faga’alu, American Samoa

Faga’alu

• Population: 1,006

• Rainfall: 155-165 inches / year

• Nestled in valley of Matafao Peak

• Observable impacts from sediment throughout stream and on reef flat

• During heavy rain events, the problem was exacerbated

Page 8: Erosion and Sediment Control - Faga’alu, American Samoa
Page 9: Erosion and Sediment Control - Faga’alu, American Samoa
Page 10: Erosion and Sediment Control - Faga’alu, American Samoa
Page 11: Erosion and Sediment Control - Faga’alu, American Samoa
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Objectives

• Hypothesis: There are statistically significant land-base sources of sediment that affect the stream and coral

• Identify potential land-based sources of pollution

• Statistically significant contributors of sediment to Faga’alu Stream

• Suggest environmental management practices to mitigate impacts on coral reef

Page 13: Erosion and Sediment Control - Faga’alu, American Samoa

Methods

• Participatory, Learning, and Action (PLA) – Community outreach

– Understand potential land-based sources of sediment

– Educate community and promote environmental stewardship

• Worked with intern at American Samoa Community College to help build local capacity

• Supports NOAA’s objective on “engaging local stakeholders in coastal and marine management planning” while improving “community readiness to cope with natural and human-induced coastal hazards.”

Page 14: Erosion and Sediment Control - Faga’alu, American Samoa
Page 15: Erosion and Sediment Control - Faga’alu, American Samoa

Methods

• Identify potential land-based sources of sediment

• Utilize YSI Sonde to measure turbidity

• Turbidity – measured in Nephelometric

Turbidity Units (NTU)

– The sensor uses optics to calculate the clarity of the water.

– Often used as an indicator of how much sediment is in the water.

Page 16: Erosion and Sediment Control - Faga’alu, American Samoa

• Land-Based Sources of Pollution

• LBJ Hospital

• Bridge and Road Construction

• Quarry

• Matafao Landslide

• Nine (9) Sample sites were selected

• Study commenced June 2, 2011

• Two-Hundred Fifteen (215) samples

Sampling Strategy

Page 17: Erosion and Sediment Control - Faga’alu, American Samoa

Site #9

Site #8

Site #7

Site #6

Site #5

Site #2 & 3

Site #4

Site #1

Page 18: Erosion and Sediment Control - Faga’alu, American Samoa

• Clean Water Act states turbidity measurements SHOULD NOT exceed FIVE (5) NTU

• Turbidity measurements ranged from 0 – 735 NTU

• One-Hundred Ten (110) out of Two-Hundred Fifteen (215) samples failed ASEPA Standards

Results

Page 19: Erosion and Sediment Control - Faga’alu, American Samoa

• Statistics

– Descriptive Statistics

– Box-and-Whisker Plots

– Kruskal-Wallis Test

– Mann-Whitney Test

Results

Page 20: Erosion and Sediment Control - Faga’alu, American Samoa
Page 21: Erosion and Sediment Control - Faga’alu, American Samoa

• Quarry and Construction have the HIGHEST mean and median turbidity measurements

• Sample sites upstream from the quarry have lowest turbidity measurements

Matafao landslide may not be significant source of sediment

Results

Page 22: Erosion and Sediment Control - Faga’alu, American Samoa

• Kruskal-Wallis Test

– Compares median turbidity measurements between ALL site

• Are sample populations the same or do other factors influence turbidity measurements?

Results

Page 23: Erosion and Sediment Control - Faga’alu, American Samoa

• Given the Kruskal-Wallis test, with 95% confidence, we can accept the alternative hypothesis that the sample sites have differing median values and do not belong to the same population.

• Suggests that there are factors influencing turbidity measurements

Results

Page 24: Erosion and Sediment Control - Faga’alu, American Samoa

• Mann-Whitney Test – Similar to a rank-sum test, a non-parametric test to

determine if two samples differ

– Used to determine if two sample sites have statistically different turbidity measurements

– Test utilized to assess whether QUARRY or CONSTRUCTION are statistically significant sources

Results

Page 25: Erosion and Sediment Control - Faga’alu, American Samoa

Results

Quarry

• With 95% confidence, we can accept the alternative hypothesis that turbidity measurements at the quarry tend to be greater than the turbidity measurement above the quarry

= Quarry is a statistically significant source of sediment

Page 26: Erosion and Sediment Control - Faga’alu, American Samoa

Results

Construction

• With 95% confidence, we can accept the alternative hypothesis that turbidity measurements at the construction site tend to be greater than the turbidity measurement upstream

= Construction is a statistically significant source of sediment

Page 27: Erosion and Sediment Control - Faga’alu, American Samoa

Impacts - Construction

• Construction can increase erosion

upwards of 200 times that of vegetated

land (Georgia Soil and Water Conservation Commission)

• Uncovered land increases runoff directly into the stream culvert

Page 28: Erosion and Sediment Control - Faga’alu, American Samoa

Impacts - Quarry

• Uncovered land increases impacts of erosions

• Other impacts:

• Loss of habitat

• Noise

• Dust and air quality

• Chemical spills and heavy metals

Page 29: Erosion and Sediment Control - Faga’alu, American Samoa

Impacts – Faga’alu Bay

• Sediment enters the bay continually from the stream

• Settles and destroys coral habitat

• Siltation harms coral and transition from coral dominated to algal dominated community

Page 30: Erosion and Sediment Control - Faga’alu, American Samoa

Environmental Management Practices

• Riparian zone in need of management practices

• Coastal Vegetation – Vetiver Grass

• Sediment Traps

• Organic Matter Cover

• Silt Fences

http://www.flickr.com/photos/normvanthoff/sets/72157622408840550/detail/ http://midwestboatparty.com/forum/showthread.php?23264-Acreage-Home-Construction-Project

Page 31: Erosion and Sediment Control - Faga’alu, American Samoa

Environmental Management Practices

• Ideally, in order to be in compliance with American Samoa Environmental Protection Agency protocol, the quarry should move machinery to at least fifty feet from the stream bank.

Page 32: Erosion and Sediment Control - Faga’alu, American Samoa

Follow-Up

• My research has alerted CRAG and the PNRS Board.

• Beginning enforcement of environmental management practices throughout the island

• PNRS Board reviewing quarry and construction permit

• Quarry and construction representatives asked to conduct Environmental Assessment and make improvements of management practices or permit will be revoked

Page 33: Erosion and Sediment Control - Faga’alu, American Samoa

Summary

• The QUARRY and CONSTRUCTION are statistically significant sources of land-based pollution

• Steps are being taken throughout community to mitigate impacts of land-based sources of pollution

• Project succeeding in addressing key NOAA mandates from the National Marine Sanctuaries Act, the Coastal Zone Management Act, and the Coral Reef Conservation Act

Page 34: Erosion and Sediment Control - Faga’alu, American Samoa

Acknowledgements

NOAA Office of Education

Lauren Wetzell (ASCMP)

Emily Gaskin (FBNMS)

Phil Wiles (ASEPA)

Christin Reynolds

(GIS Lead)

Hideyo Hattori (CRAG Lead)

Rocco Tinitali

NOAA

AS-DOC

FBNMS

AS-EPA

Page 35: Erosion and Sediment Control - Faga’alu, American Samoa

References • American Samoa Department of Commerce.

(2006). Statistical Yearbook 2006. Retrieved 6 29, 2011, from Statistics Division: http://www.spc.int/prism/country/as/ stats/fnl06yrbkhome.pdf

• Craig, P. (2009). Natural History Guide to American Samoa. In P. Craig (Ed.). Pago Pago: National Park Service.

• DiDonato, G. T. (2005). Nitrogen and phosphorus concentrations in tropical Pacific insular streams: historic data from Tutuila, American Samoa. Micronesica , 37 (2), 235-247.

• Georgia Soil and Water Conservation Commission. (2002). Erosion and Sediment Course Manual .

• Hirsch, D. H. (2010, March 23). Statistical Methods in Water Resources. Retrieved July 13, 2011, from USGS: http://pubs.usgs.gov/twri/twri4a3/ht ml/pdf_new.html

• Langer, W. H., & Arbogast, B. F. (1998). Environmental Impacts of Mining Natural Aggregate. In A. G. Fabbri, G. Gaal, & R. B. McCammon (Eds.), Deposit and Geoenvironmental lModels for Resource Exploitation and environmental Security (pp. 151-168). Netherlands: Kluwer Academic Publishers.

• US Environmental Protection Agency. (2010, February 26). Water. Retrieved July 13, 2011, from http://water.epa.gov/lawsregs/lawsgu idance/cwa/tmdl/overview.cfm

• Wong, M. (1996). Analysis of Streamflow Characteristics for Streams on the Island of Tutuila, American Samoa. Honolulu: U.S. Geological Survey.

Page 36: Erosion and Sediment Control - Faga’alu, American Samoa

Kruskal-Wallis Test

• Null Hypothesis (Ho) = All the sample sites have no variation amongst measurements

• Alternative Hypothesis (Ha) = At least one sample site has a different distribution and the sample comes from different populations.

Degrees of Freedom

Χ20.95(8) K

8 15.51 142.18

Page 37: Erosion and Sediment Control - Faga’alu, American Samoa

Mann-Whitney Test

• Null Hypothesis (Ho): Turb(Site#6) = Turb(Site#7) The turbidity values measured downstream the quarry are equal to those turbidity values measured above the quarry

• Alternative Hypothesis (Ha): Turb(Site#6) > Turb(Site#7) Turbidity values measured downstream of the quarry tend to be higher than those turbidity values measured at above the quarry

U-value Z-score(0.95)

Converted Z-value

594 1.645 5.87

Page 38: Erosion and Sediment Control - Faga’alu, American Samoa

Mann-Whitney Test (2nd)

U-value Critical U-Value

25 <25

• Null Hypothesis (Ho): Turb(Site#5)= Turb(Site#7) The turbidity values measured downstream the construction are equal to those turbidity values measured above the quarry

• Alternative Hypothesis (Ha): Turb(Site#5) > Turb(Site#7) Turbidity values measured downstream of the construction tend to be higher than those turbidity values measured at above the quarry